The discussion below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
It is known to provide pile guides for underwater piling, see for example, Sea Steel Ltd's range of pile guides as described in WO 99/11872 (Fast Frame pile guide), WO 01/92645 (Finned Frame/Follower pile guide) and WO 03/074795 (Orientation Control pile guide). With such pile guides, piles may be driven into the seabed using hydraulic hammers, such as the IHC Hydrohammers supplied by Dutch Company IHC Hydrohammer BV.
The Fast Frame Pile Guide described in WO 99/11872 comprises a base frame and a pile guide member for guiding a pile as it is driven into a substrate when the base frame is resting thereon. The pile guide member comprises two parts, each of which is pivotally mounted on the base frame. In this way, each of the two parts is moveable relative to the base frame between an operative position and an inoperative position by rotation about a respective pivot axis. The two parts are held in the operative positions by a latch mechanism, and counterweights are provided to urge the parts into their inoperative positions when the latch mechanism is released. With such a pile guide, it is possible to drive piles fully into a substrate without having to interrupt piling to move the pile guide away from the pile once it has been introduced into the substrate, simply by releasing the latch mechanism and allowing the parts of the pile guide to rotate in their inoperative positions to prevent the pile guide fouling the hammer.
The two parts of pile guide member of the Fast Frame Pile Guide define a hollow, substantially cylindrical portion for guiding a pile therethrough, when in the operative position. The substantially cylindrical portion has a plurality of rib-like spacers welded to its inner peripheral surface. Each rib-like spacer is elongate and aligned parallel to a central, longitudinal axis of the substantially cylindrical portion. The thickness of each rib-like spacer in a radial direction is adjusted (e.g. by grinding) to provide a snug, sliding fit with a pile driven through the pile guide member. In this way the spacers are used to take up any dimensional tolerance or slack between the outer diameter of the pile and the inner diameter of the hollow cylindrical portion, albeit at additional cost. Not only does it take time to adjust each spacer, but also repeated welding and removal of spacers risks damage (e.g. heat fatigue) to the pile guide member. The same problem applies to spacers for pile guide members of other pile guides which define a substantially hollow cylindrical portion for guiding a pile therethrough, see for example the pile guides described in WO 03/074795 and WO 2007/066078, the entire contents of which are incorporated herein by reference.
The Fast Frame pile guide is extremely successful, but nevertheless the present applicant is striving to improve the original design, e.g. by reducing weight and providing a structure which is more suitable for containerization with a view to making it easier to transport/store the pile guide.